Proliferation and differentiation of myelodysplastic CD34+ cells in serum-free medium: response to individual colony-stimulating factors.

Summary. The presence of serum or contaminant cells may alter clonal development of haematopoietic progenitor cells in vitro. To investigate the pathogenesis of myelodysplastic syndromes (MDS), marrow progenitor cells from 13 MDS patients were highly purified using monoclonal antibodies including CD34 and immunomagnetic microspheres. The cells positive for CD34 in the purified cells were in the range from 87% to 98%. These purified cells were cultured in serum-free medium with individual colony stimulating factors (CSFs) to investigate whether CD34+ cells from MDS patients have abnormal responses to individual CSFs. Dose response experiments with the purified CD34+ cells and recombinant human macrophage-CSF (rM-CSF), granulocyte-CSF (rG-CSF), granulocyte/macrophage-CSF (rGM-CSF), interleukin-3 (rIL-3) or erythropoietin (rEP) were performed in serum-free fibrin clots in 11 patients. Five patients showed a diminished response to rG-CSF and one patient to rEP. In the remaining six patients the purified CD34+ cells did not respond to a stimulation of any individual CSFs. The results indicate that the progenitor cell growth abnormalities in these disorders involve a defect in the capacity of progenitor cells to respond to stimulation with G-CSF, and present direct evidence for the manner in which myelodysplastic CD34+ cells are impaired.